chemistry Chemistry is the scientific study of the properties and behavior of matter. It is a physical science within the natural sciences that studies the chemical elements that make up matter and chemical compound, compounds made of atoms, molecules a ...

, peroxides are a group of compounds with the structure , where the R's represent a radical (a portion of a complete molecule; not necessarily a

free radical A daughter category of ''Ageing'', this category deals only with the biological aspects of ageing. Ageing Biogerontology Biological processes Causes of death Cellular processes Gerontology Life extension Metabolic disorders Metabolism ...

) and O's are single

oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

atoms. Oxygen atoms are joined to each other and to adjacent elements through single covalent bonds, denoted by dashes or lines. The group in a peroxide is often called the peroxide group, though some nomenclature discrepancies exist. This linkage is recognized as a common

polyatomic ion A polyatomic ion (also known as a molecular ion) is a covalent bonded set of two or more atoms, or of a metal complex, that can be considered to behave as a single unit and that usually has a net charge that is not zero, or in special c ...

, and exists in many molecules.

General structure

The characteristic structure of any regular peroxide is the oxygen–oxygen covalent single bond, which connects the two main atoms together. In the event that the molecule has no chemical

substituents In organic chemistry, a substituent is one or a group of atoms that replaces (one or more) atoms, thereby becoming a moiety (chemistry), moiety in the resultant (new) molecule. The suffix ''-yl'' is used when naming organic compounds that conta ...

, the peroxide group will have a ��2 net charge. Each oxygen atom has a charge of negative one, as 5 of its

valence electrons In chemistry and physics, valence electrons are electrons in the outermost shell of an atom, and that can participate in the formation of a chemical bond if the outermost shell is not closed. In a single covalent bond, a shared pair forms with b ...

remain in the outermost orbital shell whilst one is occupied in the

covalent bond A covalent bond is a chemical bond that involves the sharing of electrons to form electron pairs between atoms. These electron pairs are known as shared pairs or bonding pairs. The stable balance of attractive and repulsive forces between atom ...

. Because of the nature of the covalent bond, this arrangement results in each atom having the equivalent of 7 valence electrons, reducing the oxygens and giving them a negative charge. This charge is affected by the addition of other elements, with the properties and structure changing depending on the added group(s).

Common forms

The most common peroxide is

hydrogen peroxide Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscosity, viscous than Properties of water, water. It is used as an oxidizer, bleaching agent, and antiseptic, usua ...

(), colloquially known simply as "peroxide". It is marketed as solutions in water at various concentrations. Many organic peroxides are known as well. In addition to hydrogen peroxide, some other major classes of peroxides are: *

Peroxy acids A peroxy acid (often spelled as one word, peroxyacid, and sometimes called peracid) is an acid which contains an acidic group. The two main classes are those derived from conventional mineral acids, especially sulfuric acid, and the peroxy deri ...

, the peroxy derivatives of many familiar acids, examples being

peroxymonosulfuric acid Peroxymonosulfuric acid, also known as persulfuric acid, peroxysulfuric acid is the inorganic compound with the formula . It is a white solid. It is a component of Caro's acid, which is a solution of peroxymonosulfuric acid in sulfuric acid cont ...

and

peracetic acid Peracetic acid (also known as peroxyacetic acid, or Percidine) is an organic compound with the formula CH3CO3H. This peroxy acid is a colorless liquid with a characteristic acrid odor reminiscent of acetic acid. It can be highly corrosive. Perac ...

, and their salts, one example of which is

potassium peroxydisulfate Potassium persulfate is the inorganic compound with the formula K2 S2O8. Also known as potassium peroxydisulfate, it is a white solid that is sparingly soluble in cold water, but dissolves better in warm water. This salt is a powerful oxidant, co ...

. *

Main group peroxides Main may refer to: Geography *Main River (disambiguation), multiple rivers with the same name *Ma'in, an ancient kingdom in modern-day Yemen * Main, Iran, a village in Fars Province *Spanish Main, the Caribbean coasts of mainland Spanish territ ...

, compounds with the linkage (E =

main group element In chemistry and atomic physics, the main group is the group (periodic table), group of chemical element, elements (sometimes called the representative elements) whose lightest members are represented by helium, lithium, beryllium, boron, carbon ...

). * Metal peroxides, examples being

barium peroxide Barium peroxide is an inorganic compound with the formula . This white solid (gray when impure) is one of the most common inorganic peroxides, and it was the first peroxide compound discovered. Being an oxidizer and giving a vivid green colour upo ...

(),

sodium peroxide Sodium peroxide is an inorganic compound with the formula Na2 O2. This yellowish solid is the product of sodium ignited in excess oxygen. It is a strong base. This metal peroxide exists in several hydrates and peroxyhydrates including Na2O2·2H2 ...

() and

zinc peroxide Zinc peroxide (ZnO2) is a chemical compound of zinc that appears as a bright yellow powder at room temperature. It was historically used as a surgical antiseptic. More recently zinc peroxide has also been used as an oxidant in explosives and pyrote ...

(). *

Organic peroxides In organic chemistry, organic peroxides are organic compounds containing the peroxide functional group (). If the R′ is hydrogen, the compounds are called hydroperoxides, which are discussed in that article. The O−O bond of peroxides easily b ...

, compounds with the linkage or . One example is ''tert''-butylhydroperoxide.

Nomenclature

The linkage between the oxygen molecules is known as a peroxy group (sometimes called peroxo group, peroxyl group, of peroxy linkage). The nomenclature of the peroxy group is somewhat variable, and exists as an exception to the rules of naming polyatomic ions. This is because, when it was discovered, it was believed to be monatomic. The term was introduced by Thomas Thomson in 1804 for a compound combined with as much oxygen as possible,' or the oxide with the greatest quantity of oxygen.

References

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